Abstract Base-resolution sequencing of m6A and m1A epitranscriptomes in human normal and AD brain tissues More than 150 post-transcriptionally modified ribonucleosides have been identified in various types of RNA. Recent studies reveal that post-transcriptional mRNA modifications are dynamically regulated and have broad regulatory functions in most biological processes examined. These dynamic RNA modifications represent a critical new realm for gene regulation in the form of ?epitranscriptomics?, a new field expanding at a rapid pace. Previous studies from us and others indicate critical roles of RNA m6A methylation in normal brain development and neuronal functions. Our studies also showed that the m6A modification is pervasive in human brain and intriguingly, the transcripts marked by m6A specifically in human brain are enriched with the genes that have been implicated in AD. We have further demonstrated the functional importance of the m6A pathway in AD pathogenesis using an existing AD fly model. m1A is another mRNA modification that shows the highest level in human brain among other human tissues. Our most recent development of a high-resolution sequencing approach to map m1A at base-resolution in human transcriptome has revealed over 2,000 confident m1A sites, including a number of new mRNA m1A sites with high modification fractions. This modification could terminate translation in coding regions and affect translation through induced structure changes and altered protein-RNA interactions at 5? UTRs. We propose to apply two newly developed sequencing methods from our CEGS (Center for dynamic RNA epitranscriptome) and sequence m6A and m1A at base-resolution in normal and AD human brain tissues. This effort will generate the first reference m6A and m1A epitranscriptomes in human brain tissues and will examine alternations in human AD tissues. AD fly models will be employed to determine the contribution of epitranscriptome alterations to AD pathogenesis. Enabled by the new technologies developed in our CEGS this supplement application will represent the first time such study is planned.